Staff Software Engineer: big scope project vs broad technical consultant?

First thanks a lot for the good content on Taro!

My question is: for staff software engineer to be successful, do 'big scope projects' make them qualified? or they need to provide broad technical opinions?

For example, in this post and a Linkedin post from @Rahul, 'major impact with scope larger than 25 engineers' are mentioned as a must to be successful. Assuming the context is: the team owns quite a few domains/systems, and the requirement here is to have staff engineers start an initiative to create a new one.

Meanwhile, the L5 to L6 promotion course seems to mention the staff engineers should work similar to PMs in the team as they need to set up goals for each half/year and set up directions in the roadmap. Also they should 'own the goal' for the team and ensure each project is executed smoothly and the goals for the half/year are met. Assuming the context is: the team owns quite a few domains/systems, and the requirement here is to have staff engineers be able to manage the product growth for each domains.

Of course, it is always nice to have both. But practically speaking, one engineer might not be able to drive a major initiative and meanwhile be the expert at every components to provide roadmap directions.

Can anyone please share what is the critical work for a staff engineer to provide in order to be successful ?

Thank you!